High-frequency transformer



June 8 1926. 1,587,512

w. DORNIG HIGH FREQUENCY TR NSFORMER Filed Dec. 2, 1921 WALT ER D'ORN\G-By m5 A'H'ORNLY.

Patented June 8, 1926.

UNITED STATES PATENT OFFICE.

WALTER DORNIG, OF BERLIN-STEGLITZ, GERMANY.

HIGH-FREQUENCY TRANSFORMER.

Application filed December 2, 1921, Serial No. 519,325, and in GermanyDecember 13, 1920.

The invention relates to high frequency transformers such as used forwireless telegwell known, two separated iron cores or paths for thelines of force are necessary on which, when there are continuous currentwindings and secondary windings wound in the same direction, the primarycurrents are connected in the opposite direction. Consequently theensuing secondary voltage of doubled frequency will not react on theprimary circuit, only the difference between the two cores beingeffective.

By the adoption of any other principle of frequency multiplication bytransformers, with or without continuous current magnetization, thedirection of winding of the primary and of secondary is the same, soalso the voltage of the secondary frequency corresponding to thetransformation ratio of the transformer obtains on the primary terminalsand permits a current to flow through the primary circuit in accordancewith the resistance. It is preferred, however, for different reasons,for example, in order to obtain as flat a resonance curve as possibleand a low voltage or to avoid the cost of induction coils, to use in theindividual resonance circuits as high capacities as possible withoutself induction coils, except possibly, only a small variometcr in orderto bridge over the condenser unit. This causes very nearly a shortcircuit for the voltage of the secondary frequency under circumstancesopposed to the resistance of the working circuit or, at least, aparallel connected circuit of few ohms. This is the cause of the badefliciency of frequency multiplying systems. It has heretofore beenproposed to provide in the primary circuit a so-called frequency trap toprevent a reaction of the secondary frequency on the primary circuit.This method is, however, objectionable since then whenever the secondaryfrequency is changed, the frequency trap must also be tuned to the newfrequency. This is very disadvantageous, especially for a sender whichhas to send out waves of different frequency, as with each new wave thefrequency trap then must be adjusted afresh.

According to the present invention choking coils are connected in theprimary circuit which coils may be used also for tuning but they are ofsuch size that the 1mpedanee of the primary circuit to the voltage ofhigher frequency amounts to a resistance which in relation to theworking circuit is at least double.

By these means it is possible to design the choking coil so that itgives a highly protecting resistance for all secondary frequencies inquestion, and so that even if the secondary frequency is changed theprimary circuit remains constant for all wave lengths.

The drawing shows by way of example an electrical diagram of the systemaccording to the invention.

In the drawings, 1 is the oscillation producer, 2 and 4 are the tuningcondensers, 5 is a self induction for protecting the secondaryfrequency, 6 is a frequency transformer, 7 and 8 are tuning elements forthe secondary frequency, 9 the desired coupling with the antenna.

What I do claim as my invention and desire to secure by Letters Patentof the United States is 1 In an arrangement of the kind described, analternating current generator, a fre quency transformer, a primarycircuit connected between the generator .and the transformer, a waveradiator, a secondary circuit connected between the transformer and thewave radiator, a choking coil in the primary circuit with a resistancefor the secondary frequency at least twice that of the wave radiator, acapacity in the primary circuit for tuning the same to the fundamentalfrequency, and a capacity in the secondary circuit for tuning the sameto any desired frequency in the wave radiator.

In testimony whereof I afiix my signature.

WALTER DORNIG. [L- s]

